The Locost is my first major welding project, so I'm no expert, but I got a lot of help from watching videos. One thing I learned early on is that the technique of working the torch back and forth across the seam, with a slight pause at the end points, really works for me. It makes a solid weld and a nice bead to boot, and that's using the autoset feature. My early beads looked kind of narrow and lumpy.

Thanks for the info, Nick. We have the same welder, which I actually like, so I'm not blaming the machine. It's the operator.

If you consider the joint line between the pieces to be welded the "long" side, I take it you are saying you work it across the long side, going back and forth across the short side? My technique, when I don't just do a stitch weld in a smooth continuous movement, is to do the movement along the length of the joint making the classic "stack of dimes", or at least my version of it.

So many of these welds are so short and on such thin material that I'm finding a simple stitch weld where I make sure the filler penetrates down through the chamfers into the joint seems to work best for me. That seems to put enough filler in place, but the underside does not sag. There again, it may be my hand speed is slower than most.

Which welding videos did you watch, Nick? I'd like to check them out.

Cheers,

Lonnie

_________________Damn! That front slip angle is way too large and the Ackerman is just a muddle.

Well, I didn't fall down a well, I've just been sidelined with a couple of items including one significant change to the tunnel structure. I started on the tunnel next because it was: 1) about the most complicated substructure in the vehicle; 2) in the middle of the chassis and hard to get to once the side rails were up; and 3) I thought it would stabilize the un-welded chassis once removed from the build table for final welding. The idea was to fully weld it up outside the chassis and then put it in place and then weld fully to the lower crossmembers at front and back.

As I started to build the tunnel, I found some members had too many complex angles and required finer cutting on the bandsaw than was really practical. Some of the RHS joins had to be cut, ground or filed appreciably by hand and I decided to redesign and simplify the structure excepting the bottom rails, which were already completed.

Redesign really meant doing a new model in 3D because I no longer had a license to the software product I used for the original design. It also meant developing some new techniques because the old software handled RHS and tubular materials extremely well, but the new software does not and has no facility to build space frames at all, unlike the first software used. Long story short, I took quite a bit of time to do the above along with handling some real-life interruptions to do other family-related things.

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File comment: Second design in the context of a simplified surrounding chassis to save time.Small-2nd-Gen-Tunnel-ISO.png [ 131.67 KiB | Viewed 463 times ]

Age does bring some degree of caution based on experience. So, when I had the narrowest part of the new design tacked together, but not tacked to the lower (old design) bottom rails, I decided to revisit the folks at Oceanside Driveline to make sure I could get the drive shaft through from the back. I'm sure glad I did. We took a new spline and yoke, the parts I'll need to use for real, and tried to put them through the redesigned structure. There was about 0.030" extra clearance on one end and about 0.040" too little on the other end. I can't make it wider without going past the outside faces of the already-built lower rails, which would cause problems with the sheet material for the sides when affixed later.

I can force the pieces apart just enough and the tack/weld them in place, but it is close, probably way too close because even a couple coats of primer and paint may be enough to cause a problem. So, I'm going to re-think this again. In truth, I believe I could do a redesign in 1/2" x 1/2" RHS of 14 gauge just for this narrow part and do fine, strength wise. I don't expect huge forces in this part of the tunnel. That would give me a whole half inch of additional clearance, but cause some issues where the half inch RHS has to join larger 0.75" and 1" RHS pieces at front and back.

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File comment: Already built lower rails with new section set in place, but not welded.2nd-Gen-Tunnel-1.jpg [ 109.82 KiB | Viewed 463 times ]

Anyway, I'm going to take a day and give it a think-think. I really don't want to throw away the all time, work and material put in thus far, but it may be the best decision long term and I may just make a wider tunnel.

Cheers,

_________________Damn! That front slip angle is way too large and the Ackerman is just a muddle.

Sometimes when I was building the frame it felt like most of the work was on the tunnel. It does have a lot of tubes and most of them don't have straight ends. I built the sides flat on my work table, but once I started attaching things to the frame I had to use a lot of makeshift jigs to get everything lined up. I did find that 1"x1/2" RHS was both skinny and easy to match with the 1" square tubes on the rest of the frame.

Joined: October 6, 2009, 9:29 amPosts: 6812Location: Tallahassee, FL (The Center of the Known Universe)

Yo Lonnie-Remember the disclaimer, "I ain't no engineer!"

Boiled down to the simplest of terms, your choices are 1) Same footprint, smaller tubing -vs- 2) Same tubing, larger footprint. So, can you afford to give up seating width? If you're saying "No" then go with smaller tubing.

The problem you mentioned with going wider across the tunnel is that the sheet metal wouldn't mate with the edges of the bottom rails if the top were wider. Does it have to? I know you want it to, but, could you give yourself another 1/4 inch on both sides and then bend a flange in the bottom of the "skin" and rivet/weld/glue/bubblegum it to the floor?

For that matter could you make the tunnel taper smaller as it goes downward? Might look a bit funny, or might not even be visible after the seats go in.

OK, I've babbled enough... Any of this useful to you??? I'm sure you'll find the right answer. Hornitos may help... Or not...JD Kemp

_________________JD, father of Quinn, Son of a... Build LogQuinn the Slotus:Ford 302 Powered, Mallock-Inspired, Tube Frame, Hillclimb Special "Gonzo and friends: Last night must have been quite a night. Camelot moments, mechanical marvels, Rustoleum launches, flying squirrels, fru-fru tea cuppers, V8 envy, Ensure catch cans -- and it wasn't even a full moon." -- SeattleTom

I know there are strength implications to this that you would need to consider based on your specific implementation, but it would also be technically possible to notch out the tubes around the driveshaft for clearance. Making the patch out of thicker material can help a somewhat with the strength as well. I'm by no means saying it's a better plan than any others already under consideration, it just popped into my head as another alternative solution I hadn't seen mentioned.

_________________-Justin

Also follow my build on blogspot, tumblr, or instagram and twitter (GarageOdyssey)

Hi lonnie i looked for you down the well..all i could see were a pair of bright yellow eyes staring back at me way down deep..Hey could you not cut a length of 1 '' to run alongside the bottom tunnel rails thus widening it by 2'' overall then just cut your existing tunnel frame in half and rejoin it to fit

Kiwi Dave

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_________________I USE TO HAVE AN OPEN MIND ..BUT MY BRAINS KEPT FALLING OUT

Sometimes when I was building the frame it felt like most of the work was on the tunnel. It does have a lot of tubes and most of them don't have straight ends. I built the sides flat on my work table, but once I started attaching things to the frame I had to use a lot of makeshift jigs to get everything lined up. I did find that 1"x1/2" RHS was both skinny and easy to match with the 1" square tubes on the rest of the frame.

Yes, I like what you did with your tunnel, Nick. I went out today and bought 10' of both 1/2"x1/2" and 1"x1/2" so I will have material to work with over the July 4th Holiday. A lot of places will be closed multiple days. I do like the 1"x1/2" best, but wanted the flexibility of having both sizes just in case I come up with something clever. Whichever material I use, it is certain the drive shaft will fit and that's the main thing.

Cheers,

_________________Damn! That front slip angle is way too large and the Ackerman is just a muddle.

Boiled down to the simplest of terms, your choices are 1) Same footprint, smaller tubing -vs- 2) Same tubing, larger footprint. So, can you afford to give up seating width? If you're saying "No" then go with smaller tubing.

. . . <snip> . . .

For that matter could you make the tunnel taper smaller as it goes downward? Might look a bit funny, or might not even be visible after the seats go in.

. . . <snip> . . .

I was really trying to get maximum seating area since I'm making a street cruiser that I want to take on trips. I'm going to go for option 1), JD. I think I can make the center part strong enough and the extra 3 inches I've wrung out of the tunnel is going to make mama and me happier on the road.

The slanted tunnel sides would be a little to radical for me. I'm pretty traditional. Now, if it was a track car, who'd care and that would be something to consider.

Thanks for the suggestions.

Cheers,

_________________Damn! That front slip angle is way too large and the Ackerman is just a muddle.

I know there are strength implications to this that you would need to consider based on your specific implementation, but it would also be technically possible to notch out the tubes around the driveshaft for clearance. Making the patch out of thicker material can help a somewhat with the strength as well. I'm by no means saying it's a better plan than any others already under consideration, it just popped into my head as another alternative solution I hadn't seen mentioned.

That's a sensible suggestion, Justin. The only problem is that I don't know yet exactly where within the tunnel the drive shaft will lie at static ride height, or how much it will move in bump and droop. I think I'd better give myself some room all the way up and down so I don't risk being off in calculation. The smaller materials will allow me to salvage the extra seat width too, which is important in my case.

Thanks for the idea, though.

Cheers,

_________________Damn! That front slip angle is way too large and the Ackerman is just a muddle.

Hi lonnie i looked for you down the well..all i could see were a pair of bright yellow eyes staring back at me way down deep..Hey could you not cut a length of 1 '' to run alongside the bottom tunnel rails thus widening it by 2'' overall then just cut your existing tunnel frame in half and rejoin it to fit

Kiwi Dave

That is a very clever idea, Dave. It would work great. However, I really want that extra seat width for the reasons I explained to JD above. Good going, though. Give yourself an a big "atta-boy."

Cheers,

_________________Damn! That front slip angle is way too large and the Ackerman is just a muddle.

There's always 1" x 1/4" bar stock, it's approved for driveshaft safety hoops by SCCA etc. where as your smaller tubing isn't. Available at Home depot etc. So now your backup plans can have backups! Good luck.

Joined: October 6, 2009, 9:29 amPosts: 6812Location: Tallahassee, FL (The Center of the Known Universe)

Lonnie-S wrote:

laserracer wrote:

Hi lonnie i looked for you down the well..all i could see were a pair of bright yellow eyes staring back at me way down deep..Hey could you not cut a length of 1 '' to run alongside the bottom tunnel rails thus widening it by 2'' overall then just cut your existing tunnel frame in half and rejoin it to fit Kiwi Dave

That is a very clever idea, Dave. It would work great. However, I really want that extra seat width for the reasons I explained to JD above. Good going, though. Give yourself an a big "atta-boy."Cheers,

Yo, Kiwi Dave- Me and you should be the last people in here to criticize anybody for wanting plenty of room for a wide arse...

JDK

_________________JD, father of Quinn, Son of a... Build LogQuinn the Slotus:Ford 302 Powered, Mallock-Inspired, Tube Frame, Hillclimb Special "Gonzo and friends: Last night must have been quite a night. Camelot moments, mechanical marvels, Rustoleum launches, flying squirrels, fru-fru tea cuppers, V8 envy, Ensure catch cans -- and it wasn't even a full moon." -- SeattleTom

There's always 1" x 1/4" bar stock, it's approved for driveshaft safety hoops by SCCA etc. where as your smaller tubing isn't. Available at Home depot etc. So now your backup plans can have backups! Good luck.

That's something to consider, Marcus. The U-joints will be in front of and behind the section we've been discussing, but I have worried about the issue of "what happens if one end or the other breaks?". I was thinking of 16 gauge sheet on the insides of the front and rear sections containing the U-joints would be enough, reasoning that the shaft itself (only 2-1/2" diameter would pretty much stay inside the small rectangular section, and maybe just bend the tunnel tubing.

Flat stock is definitely worth serious consideration. Thank you.

Cheers,

_________________Damn! That front slip angle is way too large and the Ackerman is just a muddle.

The only problem is that I don't know yet exactly where within the tunnel the drive shaft will lie at static ride height, or how much it will move in bump and droop. I think I'd better give myself some room all the way up and down so I don't risk being off in calculation. The smaller materials will allow me to salvage the extra seat width too, which is important in my case.

Great points. It turns out that I was completely thinking about it from a IRS perspective rather than a live axle at the time...Sometimes I swear I'd forget my head if it wasn't attached to my body. Sounds like you've got some good potential solutions cooking.

_________________-Justin

Also follow my build on blogspot, tumblr, or instagram and twitter (GarageOdyssey)

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